Grade 2 · Maths · Lessons
Rows and columns
🥚egg carton🍫chocolate bar🪟window panes🧱wall
Arrays.The big ideaCount one row. Add it once for every row.
How it works
An array is a set of things in rows and columns.
Count one row, then add it once for every row.
A column is up and down. You get the same total from rows or columns.
Example 1: A few rows
- 2 rows of 3: ? + ? = ?
- Count one row.
- Add it for every row.
- So the answer is 3, 3, 6.
Example 2: More rows
- 4 rows of 2: ? + ? + ? + ? = ?
- Count one row.
- Add that row once for every row.
- So the answer is 2, 2, 2, 2, 8.
Example 3: Columns instead
- 3 columns of 4: ? + ? + ? = ?
- A column goes up and down. Count one column.
- Add it once for every column.
- So the answer is 4, 4, 4, 12.
Words to know
- array
- Objects in equal rows and columns.
- row
- Things in a line across.
- column
- Things in a line up and down.
Watch out
- Rows go across. Columns go up and down.
- Add one row once for each row, not once more.
- Rows and columns give the same total.
Try it
- 4 rows of 2: ? + ? + ? + ? = ?
- 2 rows of 3: ? + ? = ?
- 2 rows of 4: ? + ? = ?
Answers: 1. 2, 2, 2, 2, 8 · 2. 3, 3, 6 · 3. 4, 4, 8
For grown-upsUse an egg carton or a muffin tin: ask how many in a row, how many rows, and how many in all.